Hello all I'm adding this to provide some more information about this issue which lots of people seem to have seen: I've not got a full solution yet, but I can CONFIRM an oddball workaround which does work.
PROBLEM (as I experienced it):
I have an ~2006 HP Thinkpad (=Compaq 4200) with Lubuntu 11.04 and it has been FINE since I first installed that OS. Wireless worked normally ALWAYS. If I chose to "untick" Wireless on this OS, it would disable, and it could then be re-"ticked" to e-enable the wireless. All fine.
Three days ago I updated to Lubuntu 13.04: INITIALLY, all was well - Wireless up and working as normal.
BUT: then, I un-ticked the Wireless Network option: it disabled, BUT THEN ALSO GREYED-OUT the option to re-tick it - which became impossible to do. NOTHING I could then find would re-enable it: the forums showed all sorts of ideas, and like other people I saw that RFKILL now showed a HARD BLOCK on the wireless. Trying rfkill unblock all achieved nothing. Also, the external wireless on/off button now does nothing.
BUT(2): IMPORTANT SYMPTOM: I now found that if I rebooted the machine, and again booted into the original 11.04 (on another drive partition), that booted normally, but now with the Wireless icon there too, unticked and also greyed out. So 11.04 was now ALSO not able to open the WLAN port. This confirms that the issue is very low level indeed: it must be something set down at BIOS (or device-config) level, well below the OS, else two different operating systems could not both see the same issue (caused in 13.04, present in either 13.04 or 11.04).
This led me to try answer no.3 from My wireless has suddenly became disabled by hardware switch, BIOS, rfkill, fn+f8 do nothing
Note that this is SPECIFICALLY:
a. Power down and REMOVE BATTERY
b. HOLD POWER SWITCH for 30 SEC (attempts to power-up so empties internal capacitors)
c. Power on, interrupt boot with BIOS Setup access and choose RESTORE DEFAULTS
d. Reboot
If you do ALL OF THOSE, the problem clears. If you only do a. and c., it doesn't.
This is a wierd low-level issue, seemingly caused at the moment 13.04 "trod" on the device at disable time: something improper must have been delivered to the device or its BIOS parameters (I speak as an old hardware engineer.. :)
I hope this helps someone - plainly this issue is nothing to do with type of machine: has been reported on all sorts.
Apologies if you've already solved this further - in which case please tell me :)
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UPDATE 15:00 16-NOV-2013
BUT I HAVE MADE MORE PROGRESS - A FIX I THINK:
I did the following (AFTER having restored the Wireless with the actions above, under 11.04 which I have on one partition):
a. Rebooted into 13.04
b. Wireless AGAIN GREYED OUT
c. Opened console
d. Tried rfkill list
- result lists
phy0
andhp-wifi
BOTH softblocked and hardblocked.
e. Tried
sudo rfkill unblock wlan
sudo rfkill unblock wifi
f. rfkill list
NOW shows both phy0
& hp-wifi
Soft UNblocked and Hard UNblocked;
g. NOW look at Wireless icon on taskbar: Wireless still greyed out.. BUT ---
h. UN-ticked 'Enable Networking' to disable all;
j. RE-ticked 'Enable Networking' - WIRELESS OPTION TICKBOX NOW AVAILABLE AGAIN
K. RE-ticked 'Enable Wifi' - * WIRELESS WORKING !!! * CRACKED IT!
rfkill unblock all
? Run this command in a terminal. If that doesn't resolve the issue, turn off wireless hardware switch, turn back on & executedmesg | tail -n 10
. Copy the output & include in your question.